ANALYSIS OF METHICILLIN-RESISTANT AND METHICILLIN-SUSCEPTIBLE STAPHYLOCOCCUS-AUREUS BY A MOLECULAR TYPING METHOD BASED ON COAGULASE GENE POLYMORPHISMS

A molecular typing method for Staphylococcus aureus based on coagulase gene polymorphisms (coagulase gene typing) was evaluated by examining a total of 240 isolates which comprised 210 methicillin-resistant S. aureus (MRSA) and 30 methicillin-susceptible S. aureus (MSSA) collecte d from a single hospital. By AluI restriction enzyme digestion of the PCR-amplified 3'-end region of the coagulase gene including 81-bp repe ated units, the MRSA and MESA isolates examined were divided into 6 an d 12 restriction fragment length polymorphism (RFLP) patterns, respect ively, whereas five patterns were commonly detected in MRSA and MSSA. MRSA isolates that showed a particular RFLP pattern were considered to be predominant in the hospital. Coagulase typing with type-specific a ntisera was also performed for all S. aureus isolates for comparison. Coagulase types II and VII were most frequently detected and included isolates with four and five different AluI RFLP patterns, respectively , whereas each of the other coagulase types corresponded to a single R FLP pattern. These results indicated that RFLP typing was more discrim inatory than serological typing, for typing S. aureus and demonstrated its utility in epidemiologic investigation of S. aureus infection in hospitals.